Amorphous hybrid TiO2 thin films: The role of organic ligands and UV irradiation

[Display omitted] •TiO2-organic hybrid thin films with four different ligands were prepared by sol-gel.•The addition of organic complexants gives long-term stability of the precursor sol.•Drying at 80 °C gives hybrid amorphous films with enhanced functional properties.•The nature of complexing ligand influences the microstructural and surface features.•UV irradiation of the films modifies their structure and increases their conductivity. The development of a simple, economic and low-temperature synthesis procedure for titanium oxide thin films is an important challenge, due to their diffusion and to the limitations imposed by high temperature annealing. The knowledge on the properties of amorphous TiO2 films, as well as on the effect of their functionalization by organic compounds, is still inadequate. Here we describe a hydrolytic sol-gel procedure to prepare TiO2-based hybrid (inorganic-organic) thin films containing four different complexing agents in their structure (acetylacetone, dibenzoylmethane, citric acid and diethanolamine). The process variables were explored in order to attain stable sols and to tune the features of the amorphous films resulting by drying at 80 °C. Their structural, morphological, optical and electrical properties were studied by SEM, AFM, XRD, ellipsometry, FT-IR and UV–vis-NIR spectroscopy and resistivity measurements. The effect of the organic component, precursors concentration, deposition parameters and annealing temperature was considered. Moreover, the modifications induced by the exposure of the hybrid films to UV light were deeply investigated. A short UV treatment has a strong impact on the microstructure and wettability of the films and promotes a striking increase in their electrical conductivity.